薄壁圆钢管再生混合柱-钢筋混凝土梁节点的抗震试验与数值模拟

Seismic tests and numerical simulations on beam-to-column joints with demolished concrete blocks filled in thin-walled circular steel tubular columns

提出一种连接薄壁圆钢管再生混合柱与钢筋混凝土梁的加强环筋节点,开展了6个加强环筋节点和2个内加强环节点的抗震试验,考察废弃混凝土取代率和近节点域构造参数对试件抗震性能的影响。采用ABAQUS程序建立加强环筋节点的有限元计算模型,对试件进行单调荷载作用下的数值模拟。研究表明:①废弃混凝土取代率为33.3%时,试件的破坏形态和滞回曲线形状等与全现浇试件差别很小,但前者的初始刚度比后者略低;②废弃混凝土在钢管内的填筑区域改变对加强环筋节点的力学性能影响有限;③实际工程中厚壁钢管出节点域长度可取为钢管外径的一半;④在设置4根加强环筋的情况下,加强环筋节点具有不低于内加强环节点的初始刚度;⑤加强环筋节点为半刚性节点,厚壁钢管厚度和加强环筋直径对节点刚度影响较大。研究发现,钢管局部加厚的加强环筋节点是一种有效的节点形式,有利于促进薄壁圆钢管再生混合柱在中低层建筑中的应用。

Abstract： A through-column-type joint, connecting RC beam to thin-walled circular steel tubular column filled with demolished concrete blocks （DCBs）, is designed. Seismic tests of 6 joints with stiffening rings （JSR） and 2 joints with internal diagrams （JID） were conducted. The influences of both the replacement ratio of DCBs and the local detailing adjacent to panel zone on seismic performances of the specimens were investigated. The finite element analysis using ABAQUS software was conducted to simulate the monotonic behaviors of the JSR specimens. Following conclusions can be made： （1） the failure mode and profile of hysteretic curve of the specimen with 33.3% replacement ratio of DCBs are similar to those of the specimens with fresh concrete alone, while the initial stiffness of the former is little lower than that of the latter; （2） the mechanical properties of the specimens are not sensitive to the change of filling zone of DCBs in the tube ; （3） the protruded length of the thick tube out of the panel zone is suggested to be a half of the tube outer diameter; （4） the initial stiffness of the JSR specimen with 4 stiffening rings is comparable to that of the JID specimen ;（5） as a semi- rigid connection, the moment stiffness of the JSR specimen is significantly influenced by the thickness of the thick tube and the diameter of the stiffening tings. The proposed joints with stiffening rings and increased steel tube thickness in the panel zone are generally feasible, which are beneficial to the potential application of the thin-walled circular steel tubular columns filled with DCBs in low-and mid-rise buildings.